import cv2
import numpy as np
#when mouse down,set True
drawing = False
#if mode=true draw a rectangle
mode = True
ix,iy = -1,-1

#callback function
def draw_circle(event,x,y,flags,param):
	global ix,iy,drawing,mode
	if event == cv2.EVENT_LBUTTONDOWN:
		drawing = True
		ix,iy=x,y
	elif event==cv2.EVENT_MOUSEMOVE and flags==cv2.EVENT_FLAG_LBUTTON:
		if drawing == True:
			if mode == True:
                		cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),-1)
			else:
				cv2.circle(img,(x,y),3,(0,0,255),-1)          
	#when mouse release,stop drawing
	elif event ==cv2.EVENT_LBUTTONUP:
		drawing == False

img = np.zeros((500,500,3),np.uint8)
cv2.namedWindow('image')
cv2.setMouseCallback('image',draw_circle)

while(1):
    cv2.imshow('image',img)
    k=cv2.waitKey(1)
    if k ==ord('m'):
        mode=not mode
    elif k==ord('q'):
        break
cv2.destroyAllWindows()
